山东省小麦纹枯病为害损失及防治指标的研究

通过44个品种83块麦田小麦纹枯病为害损失的测定,明确小麦纹枯病可引起小麦显著减产。病级1～4级,穗粒数降低依次为3.39％、4.68％、5.97％、15.99％,但差异并不显著。千粒重降低依次为2.15％、5.74％、10.53％、18.66％,减产依次为7.21％、12.22％、25.05％、37.72％,千粒重降低是减产的主导因素。同一病级的为害损失,品种间有明显的差异,表现出耐病和敏感的不同,稻茬小麦损失大于玉米茬小麦。小麦群体病株率(X_1)和病情指数(X_2)与产量损失率(L)的关系符合二次曲线:L=0.2072X_1-8.0747×10~(-5)X_1~2-1.4937(n=67,R=0.7181),L=0.4346X_2-3.4835×10~(-4)X_2~2-0.8787(n=67,R=0.7530)。防治适期在小麦返青拔节期3月15日前后。小麦纹枯病防治指标商榷为病株率15％,或病情指数4％。     

转录调控因子AbrB对生防短短芽胞杆菌X23中抗生素edeines生物合成的影响

非核糖体类抗生素edeines是短短芽胞杆菌Brevibacillus brevis X23产生的主要抑菌物质，提高其产量有助于增加生防效果。通过全基因组测序及生物信息学分析挖掘短短芽胞杆菌X23的全局性调控因子，基于Red/ET同源重组技术构建温敏型敲除载体，通过双交换同源重组技术获得短短芽胞杆菌X23全局性转录负调控因子缺失的突变株，然后采用平板抑菌、液相色谱-质谱联用（HPLC-MS）和实时荧光定量PCR研究了全局性转录负调控因子敲除对短短芽胞杆菌X23不同生长时期发酵液的抑菌活性、edeines产量、ede操纵子转录水平的影响。从短短芽胞杆菌X23基因组中挖掘到了1个全局性转录负调控因子AbrB，敲除abrB基因后edeines生物合成基因簇操纵子的转录水平在生长前期显著提高，在发酵48 h后abrB突变株中edeine A和edeine B总产量比出发菌株提高了1.1倍。结果显示短短芽胞杆菌X23中AbrB是edeines生物合成过程中的负调控因子，敲除abrB提高了edeines的产量。     

虎杖中白藜芦醇苷不同检测方法的比较

[目的]分析比较不同方法测定的人工栽培虎杖中白藜芦醇苷的含量差异。[方法]采用高效液相色谱法(HPLC)和毛细管电泳法(CE)对人工栽培虎杖中白藜芦醇苷进行测定,并对这2种方法的线性范围、定量重现性、最低检测限及分离分析时间进行比较研究。[结果]选定HPLC-FD为测虎杖中白藜芦醇苷的最佳检测方法。检测条件:色谱柱为Diamonsil-C18(250 mm×0.46 mm,5μm),激发波长为334 nm,发射波长为408 nm,流动相为浓度25%乙腈,流速为1.0 ml/min,柱温为25℃,进样量为10μl。[结论]高效液相色谱法是测定虎杖中白藜芦醇苷含量较理想的方法。     

Estimating Reference Evapotranspiration Under Inaccurate Data Conditions

Reference evapotranspiration (ET₀)estimates have been computed on a globalscale using a high-resolution monthlyclimate dataset. Penman-Monteith (PM) andHargreaves (HG) methods have been compared,showing very reasonable agreement betweenthe two methods. Fitting the two parametersof HG using the PM derived ET₀ valuesdid not improve estimates by the HG methodsubstantially. Modifying the originalHargreaves method to a Modified-Hargreaves(MH) method by including a rainfall termimproved ET₀ estimates significantlyfor arid regions. When a certain level ofinaccuracy in the meteorologicalobservations was assumed, calculatingET₀ by PM and MH, given theseinaccuracy in observations, showed that MHperformed better than PM in reproducingoriginal calculations of ET₀ ascalculated by PM assuming no data error. Itis concluded that the PM is a recommendedmethodology if accurate weather datacollection can be expected, but otherwiseMH should be considered.     

MET对大豆群体发育及光合产物分配的影响

MET(Multi-Effect Triazole,多效唑)是一种新型植物生长延缓物质,在大豆始花期喷施200ppmMET,使植株个体矮壮紧凑,群体封行推迟,并提高了株间的透光率;同时,MET处理,使单株同化~(14)CO_2量显著增加,越接近成熟期喂饲~(14)CO_2,同化物向籽粒中运输的越多。MET处理对~(14)C同化物运砖的调节作用,主要表现在增加~(14)C同化物向根系及籽粒的运转。     

Effects of partial root-zone drying on yield,tuber size and water use efficiency in potato under field conditions

Water resources are limited for irrigation worldwide; therefore, there is a need for water-saving irrigation practices to be explored. Partial root-zone drying (PRD) is a new water-saving irrigation strategy being tested in many crop species. Experiments were conducted in potato (Solanum tuberosum L. cv. Folva) under open field conditions in 2004 and under a mobile rainout shelter in 2005. Two subsurface irrigation treatments were studied: full irrigation (FI) receiving 100% of evaporative demands, 50.1 and 201 mm of irrigation water in the 2 years, to keep it close to field capacity; and PRD, which received 21.7 and 140 mm of irrigation in 2004 and 2005 respectively. Due to rain in 2004, the PRD treatment was imposed over a short period only during the late tuber filling and maturing stages. In 2005, the PRD treatment was imposed during the whole period of tuber filling and tuber maturation. The PRD treatment was shifted from one side to the other side of potato plants every 5–10 days. Especially in 2005 it was apparent that stomatal conductance was generally lower in the PRD than in the FI plants, whereas leaf water potential tended to be lower in only a few instances. During the treatment period, plants were harvested five times, and no significant difference was found between the treatments in leaf area index, top dry mass and tuber yield. At final harvest, tubers were graded based on size into four classes C₁–C₄, of which the yield of the important marketable class (C₂) was significantly higher (20%) in the PRD than in the FI treatment. Compared with FI, the PRD treatment saved 30% of irrigation water while maintaining tuber yield, leading to a 61% increase of irrigation water use efficiency. The limited data of 2004 support these results. In summary, PRD is a promising water-saving irrigation strategy for potato production in areas with limited water resources.     

Comparison of two remote sensing models for estimating evapotranspiration: algorithm evaluation and application in seasonally arid ecosystems in South Africa

Remote sensing tools are becoming increasingly important for providing spatial information on water use by different ecosystems. Despite significant advances in remote sensing based evapotranspiration (ET) models in recent years, important information gaps still exist on the accuracy of the models particularly in arid and semi-arid environments. In this study, we evaluated the Penman-Monteith based MOD16 and the modified Priestley-Taylor (PT-JPL) models at the daily time step against three measured ET datasets. We used data from two summer and one winter rainfall sites in South Africa. One site was dominated by native broad leaf and the other by fine leafed deciduous savanna tree species and C₄ grasses. The third site was in the winter rainfall Cape region and had shrubby fynbos vegetation. Actual ET was measured using open-path eddy covariance systems at the summer rainfall sites while a surface energy balance system utilizing the large aperture boundary layer scintillometer was used in the Cape. Model performance varied between sites and between years with the worst estimates (R²<0.50 and RMSE>0.80 mm/d) observed during years with prolonged mid-summer dry spells in the summer rainfall areas. Sensitivity tests on MOD16 showed that the leaf area index, surface conductance and radiation budget parameters had the largest effect on simulated ET. MOD16 ET predictions were improved by: (1) reformulating the emissivity expressions in the net radiation equation; (2) incorporating representative surface conductance values; and (3) including a soil moisture stress function in the transpiration sub-model. Implementing these changes increased the accuracy of MOD16 daily ET predictions at all sites. However, similar adjustments to the PT-JPL model yielded minimal improvements. We conclude that the MOD16 ET model has the potential to accurately predict water use in arid environments provided soil water stress and accurate biome-specific parameters are incorporated.     

Ameliorating water repellency under turfgrass of contrasting soil organic matter content: Effect of wetting agent formulation and application frequency

Water conservation strategies are being developed in regions of the world expected to experience decreases in water resources due to changing climates. Strategies advocated for improving water-use efficiency may increase the incidence of soil water repellency in sandy-textured soils. We evaluated the effect of soil wetting agent formulation, and application frequency, on water repellency in sandy soil with two contrasting organic matter (OM) contents under kikuyugrass [Pennisetum clandestinum (Holst. Ex Chiov)], and irrigated at 60% replacement of net evaporation in a climate subject to hot, dry summers. The randomized plot design included two turfgrass ages [established from 20 week (7.7% OM) or 20 year old (30% OM) turfgrass in 2005, the latter included a 50 mm ‘mat’ layer], two soil wetting agent formulations (granular or liquid); two application frequencies (one or two applications per irrigation season); and plots of both turfgrass ages that did not receive any wetting agent (nil control). Both wetting agent formulations contained the same active ingredient (propylene oxide-ethylene oxide block polymer), and all wetting agent treatments received the same rate (69 L active ingredient ha⁻¹). Water repellency in the surface soil (0-5 mm), measured using the molarity of ethanol droplet test (MED), ranged from 1.09 M to 4.32 M during the irrigation season, and was more severe in the soil with high OM (average MED, 3.3 M) than low OM content (average MED, 2.7 M). Applying one application of either granular or liquid soil wetting agent at the commencement of the irrigation season decreased the severity of soil water repellency by up to 30% in the high OM soil and by up to 60% in the low OM soil during the summer, and without the need for a second application. The decline in soil water repellency in response to soil wetting agent application was not matched by an increase in soil VWC in summer, and turfgrass quality was considered acceptable throughout the study. The soil wetting agents were less effective at treating water repellent sand containing a significant amount of OM than sand with low OM content.     

Rootstocks influence fruit oleocellosis in ‘Hamlin’ sweet orange (Citrus sinensis L. Osbeck)

Oil spotting or oleocellosis, is a major problem in citrus crops. As the rootstock and fertilization play important roles in citrus growth and fruit development, we investigated the influence of different rootstocks on the growth, mineral nutrition metabolism, water relations, and fruit oleocellosis of eight-year-old field ‘Hamlin’ sweet orange trees. Trees grafted onto Lichi16-6 trifoliata (Poncircus trifoliate) had the greatest rate of oleocellosis (RO), and trees grafted onto Goutou orange (Citrus aurantium) had the greatest degree of oleocellosis (DO). In contrast, trees grafted onto Rangpur lime (Citrus limonia Osbeck) had the lowest RO and DO. Trees were the most vigorous on Rangpur lime rootstocks, followed by Lichi16-6 trifoliata, and then Goutou orange. In addition, because the scion/stock girth ratio showed significant correlations with the RO and DO, oleocellosis parameters can be a good indicator of scion/stock affinity. The total N, total P, Ca²⁺, and Mg²⁺ in leaves from trees on Rangpur lime were significantly lower than in leaves from trees on Goutou orange or Lichi16-6 trifoliata. In addition, the RO showed a significant correlation with the leaf Ca²⁺ and S concentrations and with the peel Mg²⁺ concentration. The DO was significantly correlated with the total peel N and S concentrations. In addition, the RO showed a significant correlation with the net assimilation of CO₂ (ACO₂), stomatal conductance (GS), transpiration rate (ET), and water-use efficiency (WUE). However, the DO showed a significant correlation with the GS, ACO₂, and WUE. Taken together, these results indicate that rootstocks affect the development of oleocellosis in ‘Hamlin’ sweet orange due to their effects on the mineral nutrition balance and water relations.